This application claims priority under 35 U.S.C. 119 to the foreign application number 9930120.2, filed on Dec. 21, 1999 in United Kingdom.
The present invention relates to monitoring equipment for monitoring the performance of an engine fuel injector valve, comprising a source of pressurized fluid and an injector valve head provided with connection means to enable an injector valve to be connected thereto, the head being connected to the source so that pressurized fluid from the source is delivered to the injector valve when the equipment is in use, there being regulator means of the equipment to compensate for changes in pressure of the fluid at the head owing to pulsed operation of the injector valve when the equipment is in use, as well as to enable a change in pressure to be effected and maintained at the head, and flow monitoring means in the fluid path between the source and the head to monitor the flow of fluid to the head.
Hitherto, air piloted pressure regulators have been used as the regulator means. However, such equipment has suffered from a relatively slow response time to pressure changes, especially because of the use of air as the control medium. This results in an undesirable level of hysteresis using such equipment.
The present invention seeks to obviate this disadvantage.
Accordingly, the present invention is directed to monitoring equipment having the construction set out in the opening paragraph of the present specification, in which the source of pressurized fluid is such as to maintain a level of pressure in excess of a desired operating pressure, and in which the regulator means comprises fluid flow control means coupled to a pressure sensor, which is in or near the test head to provide an indication of the pressure therein so that the flow control means effects an increase or a decrease to flow of fluid through the said fluid path to maintain the pressure of the fluid at the head substantially at the desired operating pressure.
Preferably, the flow control means comprises a hydraulic amplifier arranged to operate valve means of the flow control means so as to effect such increase or decrease.
An especially fast response to changes of pressure is obtainable if the flow control means comprises a first movable member, transducer means which serves to provide a force which acts on and moves the first movable member in dependence upon the magnitude of an input signal delivered to the flow control means, two inputs connected to deliver pressurized fluid to opposite sides respectively of the first movable member and to opposite sides respectively of a second movable member, and output means from which fluid flows after it has reached the first movable member, in such a manner that movement of the first movable member in a first direction increases the resistance to flow of fluid from one of the two inputs to the said output means, so that pressure of fluid from that input urges the said second movable member in a given direction, whilst movement of the first movable member in a second direction, opposite to the first, increases the resistance to flow of fluid from the other of the said two inputs to the said output means, so that pressure of fluid from that other input urges the said second movable member in another direction opposite to the said given direction, the flow control means further comprising balancing means to balance the movement of the second movable member against the said force, and valve means which are opened to an extent which is dependent upon the position of the second movable member, whereby the extent to which the valve means is opened is dependent upon the magnitude of the input signal, so that the latter effects such increase or decrease.
Advantageously, the pressurized fluid delivered by the said two inputs is the pressurized fluid from the said source.
Preferably, the balancing means comprise a spring.
The valve means of the flow control means is preferably a slide valve, for example a spool valve.